Anomalous Echoes Captured by a B-52 Airborne Radarscope Camera

Martin L. Shough

3. Frame-by-Frame Description of Radarscope Photographs

Frame 771 - The clock is set to
Zulu time or GMT, and shows 0906 and 14 seconds (0406:14
local time, CDT). The sweep has completed approximately half
of its first revolution and the 3 inner range rings are
clearly visible in the central altitude-hole area, one at
0.75 NM, another at 1.25 NM and a third, brighter, ring at
1.75 NM. This area
appears largely free of the speckling which increases later
in the sequence. The edge of the surrounding bright area of
ground return is sharply delineated at about 2.1 NM. A small
discrete echo appears at azimuth 138 degrees, ahead and a few
degrees to the right of the nose of the B-52 and just inside
the third range ring, its nearer edge measured at 1.62 NM
slant range (Note 2). This echo
appears slightly elliptical with its major axis lying
obliquely aslant the range axis.

Frame 772 - 3 seconds later, at
0906 and 17 seconds, no echo is visible at the previous
location but a similar discrete echo, distinctly elliptical
and with its major axis similarly oblique, appears at 242
degrees, 1.05 NM, aft of the right wing.

Frame 773 - 0906 and 20
seconds. Now the previous echo has decayed and a new echo,
somewhat brighter and larger, but still very discrete,
appears at 40 degrees azimuth, 1.05 NM off the left wing.
The echo is also elliptical, this time its major axis
oriented approximately on the PPI range axis. It also appears
to be accompanied by, indeed conjoined with, a much smaller
and fainter but still discrete secondary echo at slightly
greater range (~ 1.15 miles) on roughly the same azimuth. (A
very small and indistinct echo possibly also appears at about
138 degrees, range about 1.05 miles.) Picture resolution
and/or contrast is deteriorating slightly. The inner 3/4-mile
range ring is now virtually undiscernable.

Frame 774 - 0906 and 23
seconds. There is no clear target echo on this scan.
Background speckle inside the altitude hole is increasing.

Frame 775 - 0906 and 26
seconds. The noise speckling is very evident on this scan and
both the first and second range rings are virtually
invisible. Again there is no definite target echo, but a
possible return is visible cutting the 1.75 NM ring at ~350
degs. The unique brightness of this feature (Fig.2),
brighter than the brightest ground return on frame 775, may
be due to a strong echo (perhaps augmented by the underlying
range marker amplitude). Density contours measured by Claude
Poher show characteristics that appear inconsistent with a
radar noise artefact or print emulsion defect. It remains
possible but not probable that it is a slightly blurred photo
artefact introduced at print-projection stage.

Fig. 2. Detail of suspect "echo" from frame #775. The original
image (right) can be rendered at extreme contrast as a roughly
oval "blip" (left). A noise artefact amplified by a
fluctuation in the noisy 1.75 NM range ring (center) seems
unlikely in view of the photometry. A photographic artefact
remains a possibility.

Frame 776 - 0906 and 29
seconds. An echo has now reappeared at the same azimuth and
the same range as the double echo on frame 773, 40 degrees at
1.05 nautical miles. It covers the same radial extent as the
double echo on frame 773, though it is less bright and not
distinctly divided in two parts. (A pair of echoes can
arguably be identified amid the speckles at about 1.5 miles
range aft of the right wing, but they are only marginally
above the noise level and may not be significant.)

Frame 777 - 0906 and 32
seconds. There is again an echo at the same 40 degree bearing
and slightly closer at 1.0 NM. This is a single compact echo,
brighter again with no visible secondary echo and with only a
small ellipticity. As in 773 and 776, the major axis of the
ellipse is alligned approximately radially. (There is another
possible echo aft of the right wing, a radial smudge sitting
athwart the 1.75-mile range ring at 246 degrees. Possibly
this is a close pair on the same azimuth. But again the noise
level near the scope periphery means that the status of this
echo is marginal.)

Frame 778 - 0906 and 35
seconds. Another single compact echo at 40 degrees and 1.0
mile, again slightly elliptical, almost identical to 777.

Frame 779 - 0906 and 38
seconds. Now there is a double echo again, still at 40
degrees, with two slightly less distinct and less bright
components, of similar appearance, connected by a suggestion
of a faint "bridge", at about 0.9 and 1.1 miles on
the same radius.

Frame 780 - 0906 and 41
seconds. Again a single bright, compact, elliptical echo,
similar in appearance to 777 and 778, still at 40 degrees but
now at about 0.95 mile.

Frame 781 - 0906 and 44
seconds. An echo (or pair of echoes) somewhat similar in
appearance and range to 779, but now at 39 degrees azimuth.

Frame 782 - 0906 and 47/48
seconds. Still at 39 degrees, but now closer at about 0.87
NM, is a single, bright, compact and almost circular echo.

Frame 783 - 0906 and 50/51
seconds. There are no unidentified point echoes visible
during this scan. The altitude-hole area now appears free of
noise and all three range rings and the heading marker are
again distinct. The sharp edge of the surrounding ground
return is by now closer, having moved steadily inward from
about 2.15 NM slant range in 771 to about 1.8 NM in 783.